The invention relates to a storage and retrieval system including a housing accommodating a plurality of carriers movable by means of a transport device to at least one access opening provided in the housing and including a closing means arranged at the access opening for defining an access window.
One such storage and retrieval system is known from U.S. Pat. No. 5,820,237. In this known storage and retrieval system the carriers accommodating the stored items are circulated by the transport device in the housing. Provided at the access opening in the housing is a plurality of vertically movable doors, each of which can be signalled dedicated so that only a dedicated access window of the access opening is formed as a function of authorized access to thus prohibit unauthorized access.
A similar storage and retrieval system is know from U.S. Pat. No. 5,836,662 the doors of which provided at the access opening can be hinged out of the way about a horizontal axis.
Due to the plurality of doors needing to be separately actuated and signalled, the storage and retrieval systems as described above are complicated in structural design, involving high manufacturing costs.
The invention is based on the object of proposing a storage and retrieval system permitting controlled access with an uncomplicated structural design.
To achieve this object a storage and retrieval system of the aforementioned kind is proposed in which the closing means comprises at least two closing elements arranged opposite each other which can be shifted horizontally and is separately controlled.
Since the closing means in accordance with a first embodiment of the invention comprises merely two horizontally shiftable closing elements which form a dedicated access window at the access opening of the storage and retrieval system as a function of how they are controlled, an uncomplicated structural design is achieved. Since the closing elements can be infinitely adjusted horizontally the access window can be precisely controlled. To advantage each closing element comprises a linear drive connected to a position sensor. The closing means in accordance with the invention is compatible both with storage and retrieval systems having circulating carriers and with storage and retrieval systems incorporating other means for transporting the carriers. Several access openings may be provided in the storage and retrieval system in accordance with the invention, for example, at the front and rear side of the housing.
Advantageous aspects of the invention read from the sub-claims.
Advantageously, each closing element is assigned a separate drive unit. Since only a small number of closing elements is needed, the number of drive units needed is likewise small.
Advantageously, each closing element is guided on a horizontal guide provided at the access opening.
In accordance with an advantageous embodiment the closing element is configured as a roller shutter, the slats of which may be made of aluminium, for example.
Advantageously, a winder mechanism for each roller shutter is arranged at the sides of the access opening, the winder mechanism being expediently concealed by a cover plate.
In another embodiment the closing element is configured as a telescopic metal plate.
Advantageously, the closing element comprises a viewing window at least partially. The closing element may also be made of a see-thru material.
In another advantageous aspect the closing means is provided with at least one vertically travelling door fronting the at least two horizontally travelling closing elements to thus enable the access window to be defined also in its height. At the same time the fronting door, made to advantage of solid sheet steel, serves to protect the system from vandalism. Advantageously a position sensor is assigned to the fronting door.
In yet another aspect of the invention a control means is provided which controls the drive unit of the at least two closing elements.